[PR122215, IRA]: Fix undefined behaviour of improve_allocation

Register filters are used in one loop of improve_allocation to ignore some
hard regs for cost calculation but it is missed in the subsequent loop
using the costs.  This results in usage of random (undefined) register costs
and in sporadic code generation for riscv32 which uses the filters.

gcc/ChangeLog:

	PR rtl-optimization/122215
	* ira-color.cc (improve_allocation): Use register filter for all
	loop on hard regs.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/122215
	* gcc.target/riscv/pr122215.c: New.
	* lib/target-supports.exp (check_effective_target_valgrind): New.

gcc/ira-color.cc

@@ -3369,6 +3369,9 @@ improve_allocation (void)
       for (j = 0; j < class_size; j++)
 	{
 	  hregno = ira_class_hard_regs[aclass][j];
+	  if (NUM_REGISTER_FILTERS
+	      && !test_register_filters (ALLOCNO_REGISTER_FILTERS (a), hregno))
+	    continue;
 	  if (check_hard_reg_p (a, hregno,
 				conflicting_regs, profitable_hard_regs)
 	      && min_cost > costs[hregno])

gcc/testsuite/gcc.target/riscv/pr122215.c

@@ -0,0 +1,46 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target valgrind } */
+/* { dg-additional-files "sparseset.supp" } */
+/* { dg-options "-wrapper valgrind,-q,--exit-on-first-error=yes,--error-exitcode=1,--suppressions=${srcdir}/sparseset.supp" } */
+
+typedef signed int int32_t;
+typedef signed long int int64_t;
+
+int64_t dual_reg_insn(int64_t x) {
+    int64_t res;
+    int64_t zero = 0;
+    asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (zero));
+    return res;
+}
+
+int32_t single_reg_insn(int32_t x) {
+    int32_t res;
+    int32_t zero = 0;
+    asm ("some_custom_insn %0,%1,%2" : "=r" (res) : "r" (x), "r" (zero));
+    return res;
+}
+
+int32_t single_reg_insn_explicit_zero(int32_t x) {
+    int32_t res;
+    asm ("some_custom_insn %0,%1,%2" : "=r" (res) : "r" (x), "r" (0));
+    return res;
+}
+
+int64_t dual_reg_insn2(int64_t x) {
+    int64_t res;
+    int64_t zero = 0;
+    asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (zero));
+    return res;
+    /* This function is IDENTICAL to dual_reg_insn,
+     * but for some obscure reason (alignment?)
+     * it decides to use sX registers instead of aX to store zero,
+     * resulting in a much larger code since it needs to use the stack.
+     * THIS ONLY HAPPENS SOMETIMES!
+     */
+}
+
+int64_t dual_reg_insn_explicit_zero(int64_t x) {
+    int64_t res;
+    asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (0LL));
+    return res;
+}

gcc/testsuite/lib/target-supports.exp

@@ -14762,3 +14762,11 @@ proc check_effective_target_fentry { } {
 	}
     }]
 }
+
+# Check if valgrind executable exists in PATH on host
+proc check_effective_target_valgrind { } {
+    if { [which valgrind] != 0 } {
+        return 1
+    }
+    return 0
+}